Principal Investigator(s):Chatterji, Somnath, World Health Organization; Kowal, Paul, World Health Organization, and University of Newcastle

Summary:

The World Health Organization (WHO)'s Study on Global Ageing and Adult Health (SAGE) is a longitudinal follow-up of a cohort of ageing and older adults. SAGE has been built on the experience and standardized instruments of WHO's 2000/2001 Multi-country Survey Study (MCSS) and the 2002/2004 World Health Surveys (WHS).
These surveys focused on health and health-related outcomes and their determinants and impacts in nationally representative samples. These data will address data gaps on ageing, adult health and well-being in lower and m... (more info)

The World Health Organization (WHO)'s Study on Global Ageing and Adult Health (SAGE) is a longitudinal follow-up of a cohort of ageing and older adults. SAGE has been built on the experience and standardized instruments of WHO's 2000/2001 Multi-country Survey Study (MCSS) and the 2002/2004 World Health Surveys (WHS).

These surveys focused on health and health-related outcomes and their determinants and impacts in nationally representative samples. These data will address data gaps on ageing, adult health and well-being in lower and middle income countries, whilst being comparable to surveys conducted in higher income countries (such as the United States' Health and Retirement Study (HRS), English Longitudinal Study of Ageing (ELSA), and the Survey of Health, Ageing and Retirement in Europe (SHARE)). One of the major drivers of this effort has been the lack of comparability of self-reported health status in international health surveys due to systematic biases in reporting, despite using similar instruments and attempts at making questions conceptually equivalent in translation. SAGE uses standard instruments developed over the last decade, a common design and training approach with explicit strategies for making data comparable to cover a wide range of issues that directly and indirectly impact health and well-being.

The survey methodology and research design has included a number of methods to address methods for detecting and correcting for systematic reporting biases in health interview surveys, including vignette methodologies, objective performance tests and biomarkers. A number of techniques have also been employed to improve data comparability, including using common definitions of concepts, common methods of data collection and translations, rigorous sample design and post hoc harmonization. The 2007-2010 SAGE Wave 1 data from six countries (China, Ghana, India, Mexico, Russia, and South Africa) is the follow-up survey project to the 2002-2004 WHO data, which constitutes Wave 0 of WHO's Study on Global Ageing and Adult Health (SAGE). A sample of these respondents from SAGE Wave 0 are included in this follow-up 2007-2010 SAGE Wave 1 in the six countries, with new respondents added to ensure a nationally representative sample.

Access Notes

The public-use data files in this collection are available for access by the general public.
Access does not require affiliation with an ICPSR member institution.

Dataset(s)

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Universe:
Nationally representative samples of adults aged 18 years and older, residing within individual households, institutionalized population excluded, in the following countries: China, Ghana, India, Mexico, Russia, and South Africa.

Data Types:
observational data,
survey data

Data Collection Notes:

In addition to funding provided by the National Institute on Aging, Division of Behavioral and Social Research (BSR) and Interagency Agreements with WHO, the governments of China and South Africa have provided financial or other support for their national studies. Collaborating agencies in each country made in-kind contributions. USAID provided additional funds in support of SAGE India to increase the sample of women aged 15-49 as a nested study examining health in younger women.

Methodology

Study Purpose:
The specific aims of SAGE as currently formulated are: To obtain reliable, valid and comparable data on levels of health on a range of key domains for older adult populations; to examine patterns and dynamics of age-related changes in health using longitudinal follow-up of survey respondents as they age, and to investigate socio-economic consequences of these health changes; to supplement and cross-validate self-reported measures of health and the anchoring vignette approach to improving comparability of self-reported measures, through measured performance tests for selected health domains; to collect data on health examinations and biomarkers to improve reliability of data on morbidity, risk factors and monitor effect of interventions. Additional objectives include: To generate large enough cohorts of older adult populations and comparison cohorts of younger populations for follow-up of intermediate outcomes, monitoring trends, examine transitions and life events, and address relationships between determinants and health and health-related outcomes; to develop a mechanism to link survey data to data from demographic surveillance sites; to build linkages with other national and cross-national ageing studies; and, to provide a public-access information base to engage all stakeholders, including national policy makers and health systems planners, in planning and decision-making processes about the health and well-being of older adults. In addition, close linkages with the International Network of field sites with continuous Demographic Evaluation of Populations and Their Health (INDEPTH) in developing countries will ensure that detailed methodological exercises can be undertaken to validate self-reported morbidity and survey mortality data.

Sample:

The targeted sample sizes for each country are as follows: China 14813, Ghana 5110, India 11230, Mexico 2756, Russian Federation 4355, and South Africa 4223. The China and South Africa Wave 1 samples are new, and do not include any Wave 0 follow-up respondents.

The goal of the sampling design was to obtain a nationally representative cohort of persons aged 50 years and older, with a smaller cohort of persons aged 18 to 49 for comparison purposes. The target sample size was 5000 households with at least one person aged 50+ years and 1000 households with an 18 to 49 year old respondent. In the older households, all persons aged 50+ years (for example, spouses and siblings) were invited to participate. Proxy respondents were identified for respondents who were unable to respond for themselves (using the IQ Code).
In consultation with the Ministry of Health in China, China CDC and Shanghai CDC, a new sampling design was used for SAGE in China drawn from an existing national surveillance system. In India, a representative sample of six states was included, taking into consideration population size and level of development, and can be modelled to a nationally representative sample. The Russian Federation's sample was extended to the east (as compared to the Wave 0 sample) to include respondents from the "Asian" region of the country. For more information on sampling, please visit the WHO Study on Global AGEing and Adult Health (SAGE) Web site.

Time Method:
Longitudinal

Weight:

The data are not weighted, but contain four weight variables across all data parts which users may wish to apply during analysis. Household weights for analysis at household level include HHWEIGHT (Post stratified household weight) and HHWEIGHT2 (Post stratified household weight - national). Individual weights for analysis at person level include PWEIGHT (Post stratified person weight) and PWEIGHT2 (Post stratified person weight - national). Please note weights HHWEIGHT2 and PWEIGHT2 are country specific to the Russian Federation. For additional information on weights, please refer to the WHO Study on Global AGEing and Adult Health (SAGE) Web site.

Extent of Processing: ICPSR data undergo a confidentiality review and are altered when necessary to limit the risk of
disclosure. ICPSR also routinely creates ready-to-go data files along with setups in the major
statistical software formats as well as standard codebooks to accompany the data. In addition to
these procedures, ICPSR performed the following processing steps for this data collection: